Revert "mgcp_client: don't configure "bts base"" until osmo-msc is ready

OsmoMSC is in the odd situation that it is already using the new 
libosmo-mgcp-client, which is targeted at osmo-mgw, to configure talking to the
old osmo-bsc_mgcp. By removing the bts_base, we break current OsmoMSC.

Removing bts_base makes sense, but let's revert this until OsmoMSC is ready
after merging Ieea9630358b3963261fa1993cf1f3b563ff23538 (which moves the 
osmo-msc over to osmo-mgw).

This reverts commit 0be3ce66c058f39e07f7a1c93a9bf632fb936edf.

Change-Id: Ibce214c2bfc35623097abbb647619426ef3dcc94
diff --git a/src/libosmo-mgcp-client/mgcp_client.c b/src/libosmo-mgcp-client/mgcp_client.c
index 5cd14f7..ee8d267 100644
--- a/src/libosmo-mgcp-client/mgcp_client.c
+++ b/src/libosmo-mgcp-client/mgcp_client.c
@@ -45,6 +45,7 @@
 		.remote_port = -1,
 		.first_endpoint = 0,
 		.last_endpoint = 0,
+		.bts_base = 0,
 	};
 }
 
@@ -439,6 +440,7 @@
 
 	mgcp->actual.first_endpoint = conf->first_endpoint > 0 ? (uint16_t)conf->first_endpoint : 0;
 	mgcp->actual.last_endpoint = conf->last_endpoint > 0 ? (uint16_t)conf->last_endpoint : 0;
+	mgcp->actual.bts_base = conf->bts_base > 0 ? (uint16_t)conf->bts_base : 4000;
 
 	return mgcp;
 }